Denver Wildlife Research Center -- Cali, Colombia Field StationInstituto Colombiano AgropecuarioUnited States -- Agency for International Development. -- Office of Agriculture and Fisheries

Publisher:

Research Center, Centro de Investigaciones.

Place of Publication:

Palmira Columbia

Creation Date:

1984

Frequency:

annualregular

Subjects

Subjects / Keywords:

Pests -- Control -- Periodicals -- Colombia ( lcsh )

Genre:

federal government publication ( marcgt )serial ( sobekcm )

Notes

Language:

Cover title also in Spanish.

Statement of Responsibility:

Cali, Colombia, Field Station.

Dates or Sequential Designation:

1970-

Issuing Body:

Cooperating agencies: Instituto Colombiano Agropecuario, Office of Agriculture and Fisheries, Bureau of Technical Assistance, U.S. Agency for International Development, Denver Wildlife Research Center, Bureau of Sport Fisheries, U.S. Dept. of the Interior.

The cover illustrates the broad international scope of the USAID-
sponsored International Programs of the Denver Wildlife Research
Center (DWRC) and two of the most severe animal damage problems
under investigation. Research at DWRC and in the field involves
evaluating different control methods including chemical, physical,
cultural, or other techniques that have potential for providing
positive benefits by reducing vertebrate damage in agriculture. The
pest species, crop, farming and storage methods, environmental
factors, and a host of other considerations may influence the manner
in which a particular problem is approached.

Vertebrate damage in agriculture involves a variety of crops and
species of animals, primarily birds and rodents. Direct losses
occur typically at planting and sprouting, during the milk or dough
stages (for grains), just before harvest, or under posthavest
storage conditions. Field programs are involved in trying to
reduce or alleviate this damage in several countries of South and
Central America, Africa, and Asia.

In many areas of the world, rodent damage to field crops, such as
rice in Asia, severely reduces the human food supply and increases
the risks to small-farm agriculture. In localized areas, rodents
may be a principal factor limiting crop production; more often,
rodents unobtrusively remove a share of production before
harvest--crop after crop, season after season. Although there are
more than 6,000 kinds of rodents, only about 50 can be considered
significant agricultural pests.

Losses to birds are less well documented than those to rodents.
Various species of parrots, parakeets, blackbirds, weavers, doves,
seedeaters, pheasants, and waterfowl are among the types of birds
known to cause damage in agriculture around the world. Actual
losses are difficult to assess because damage is usually concen-
trated in limited areas and, due to the mobility of birds, is often
seasonal, sporadic, and hard to predict. The red-billed quelea in
Africa is perhaps the most important vertebrate pest species in the
world.

Increasing food production is one of the most important challenges
facing mankind. In some developing countries the disparity between
available food and population is both widespread and acute, despite
the fact that about one-half of the world's population is actively
engaged in agriculture. Millions of people in scores of nations
still suffer hunger, malnutrition, and starvation. The reasons are
many and complex, but certainly vertebrate pests (primarily rodents
and birds) are important factors. Historically, they have not
received the degree of attention given to other agricultural pests
so that, with few exceptions, little reliable information on the
species involved, degree of damage, and the economic impact, is
available. Damage is, however, unquestionably calculated in
hundreds of millions and perhaps billions of dollars annually.

In recent years, the role of vertebrate depredations in agriculture
is attracting more interest in developing nations. Recognizing
this, the U.S. Agency for International Development (USAID) has
supported a research program at the Denver Wildlife Research Center
of the U.S. Fish and Wildlife Service (USFWS) since 1967 under a
Participating Agency Service Agreement (PASA) as provided for in
Section 632B of the Foreign Assistance Act of 1961. The program
goal is to evaluate these situations and, when circumstances
warrant, develop methods to reduce or eliminate the damage. For
many years, DWRC has been recognized as a leading organization in
researching vertebrate pest damage problems and developing useful
tools for vertebrate pest management. Its problem-solving team
approach has led to developing and using new methods, materials, and
techniques for vertebrate pest control, resulting in monetary
savings in several developing countries.

The overall objective of this project is to increase the available
human food supply in developing countries by reducing losses to
vertebrate pests in both preharvest and postharvest situations. The
ultimate aim of the pest management research program is to develop
safe, effective, and economical control methods which are suitable
and practical for traditional farmers and acceptable in the broader
context of agricultural development. Self-sustaining, in-country
programs are the expected end result of this project. Program goals
are accomplished by (1) in-country programs, (2) outreach activities
from the DWRC as requested by USAID/Washington, USAID Missions, or
host countries, (3) supervisory and administrative functions from
DWRC and USAID/Washington, and (4) problem-oriented research activ-
ities at DWRC through the Sections of Supporting Sciences, Bird
Damage Control, Mammal Damage Control, and other components of the
Center. Vertebrate damage problems in Africa, Asia, and Latin

America are continuously reviewed with the aim of adapting current
techniques or materials to specific problem situations in a crop
protection-oriented management program which will provide an
effective means of long-term crop protection.

The project incorporates a balanced but flexible program of applied
research, technology transfer, and training. Research activities
incorporate coordinated laboratory investigations at DWRC and
selected laboratories in developing countries with associated field
trials at appropriate sites in specific problem areas. A team
approach, using the services of an interdisciplinary group of
scientists and technicians with diverse backgrounds and experience,
coupled with active involvement of foreign investigators, results
in practical solutions suited to local requirements. In addition,
it creates a favorable climate for continuing cooperation with
indigenous institutions. Training of local counterparts and
institutionalization of both research functions and implementation
programs are viewed as integral parts of the overall project.

The Section of International Programs of DWRC provides support and
direction to field personnel, assists in establishing relevant
research objectives for laboratory personnel, and coordinates the
team efforts of DWRC and cooperating scientists. The experienced
DWRC staff is composed of specialists in diverse fields such as
ecology, physiology, pharmacology, wildlife biology, nutrition,
statistics, animal psychology and behavior, chemistry, and electron-
ics. Several staff members have foreign experience and fluency in
foreign languages. Denver Center laboratories are well equipped
with the instrumentation necessary to conduct research in each of
the disciplines involved. General administrative support is pro-
vided in the areas of fiscal management, personnel matters,
commodity procurement, records management, and coordination of
correspondence, reports, and manuscripts. Related activities
include representing the program to other organizations, coordi-
nating DWRC-based training for USAID participants, briefing
visitors, developing cooperative programs with international
organizations, providing technical information to USAID Missions or
other cooperators, and assisting USAID personnel in program
development and negotiations with foreign governments.

Throughout the report, reference to trade names does not imply
endorsement by U.S. Government or cooperating foreign agencies.

During 1984, project personnel devoted much time and effort to
support field station activities and cooperate with other organiza-
tions in research and training of mutual interest.

Latin America

To address the problem of vertebrate pest damage to agriculture in
the Caribbean Region, the USAID Bureau for Latin America and the
Caribbean and DWRC established in 1979 a regional program with
special emphasis placed on those crops which are predominantly
produced by traditional farmers. The project headquarters is in
Port-au-Prince, Haiti, to serve the specific needs of Haiti and
other regional countries.

During 1984, considerable effort was made by the DWRC Project
Leader and Vertebrate Pest Laboratory staff to more completely
document the vertebrate pest problem in Haiti. Crop production
statistics were gathered and losses to vertebrate pests were
described from questionnaire surveys or quantified from actual field
assessments. Field studies evaluating flagging material as
repellent for woodpeckers that damage maturing corn and a rodent
problem survey on small farms were initiated. A study using
bird-scaring reflection tape to protect grain sorghum from birds
was conducted, and the breeding biology of village weavers was
studied.

In September, the project leader returned to the DWRC ending 5
years of direct involvement in establishing an effective Vertebrate
Pest Laboratory. DWRC will continue to provide short-term
assistance as requested by USAID/Haiti and the Ministry of
Agriculture.

Bangladesh

The Vertebrate Pest Control Laboratory (VPCL) continues to be a
highly successful research program, and staff have been begun
training extension personnel throughout the country. Because of
the excellent participation in the National Rat Control Campaign in
Wheat-1982/1983, a similar campaign was conducted in 1983/1984 in
cooperation with the Bangladesh-German (GTZ) Plant Protection
Programme. Studies were conducted to determine toxicity of
rodenticides to common rodent pests; jackal and rat damage in
sugarcane; the agricultural and economic importance of the jackal;
the sensitivity of several bird species to copper oxychloride;
simulated bird damage to sprouting wheat; myna damage to wheat
seedlings in the aviary; and the repellent effects of bird-scaring
reflection tape in maturing oilseed and grain crops.

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HAITI
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Island

REPUBLIC

A Damien Site of Field Station

HAITI

FIELD PROGRAMS

Two field stations, located in Haiti and Bangladesh and involving
resident U.S. biologists were continued during 1984 under the
USAID/DWRC program. The broad goals of these programs were to
increase food production and to reduce the risk of severe agricul-
tural losses caused by vertebrate pests in developing countries.
Specific objectives were as follows:

1. Establish the technical capabilities and support within govern-
ments and the agricultural sector to conduct programs in
vertebrate pest research and management.

2. Develop new and adapt existing practical low-cost methods and
technology to evaluate and reduce preharvest and postharvest
crop losses to vertebrate pests of significant regional
importance under local conditions.

3. Provide onsite training in research and management methods to
reduce losses by vertebrate pests.

4. Provide training at DWRC and appropriate universities to
perfect capabilities of counterparts to conduct programs in
vertebrate pest management.

HAITI

Breeding Biology of Village Weavers (Ploceus cucullatus)

Bird populations usually are lowest just before the reproductive
season. The annual production of young replenishes the number of
village weavers (Ploceus cucullatus) in Haiti, and because young
usually outnumber adults after the breeding season, the young cause
the greatest losses to grain crops in late summer and fall. In
years of poor reproduction, crop damage should be less; this seemed
to be the case in 1984.

Of ten colonies closely monitored in 1983, only five were occupied
in 1984 (Table 1). The number of active males in the colonies was
down about 70% in' 1984, and nests were about 80% fewer than in
1983. Thus, with fewer males, fewer nests, and fewer nests/male
(4.2 vs. 5.5) in 1984, undoubtedly, fewer young were produced.

Five of the colonies were located in acacia woodlands and five were
in inhabited areas on the outskirts of Port-au-Prince. In 1983,
the largest colonies were in acacia woodlands and accounted for 73%
of the nests. Only one woodland colony was active in 1984; it

FIELD PROGRAMS

Two field stations, located in Haiti and Bangladesh and involving
resident U.S. biologists were continued during 1984 under the
USAID/DWRC program. The broad goals of these programs were to
increase food production and to reduce the risk of severe agricul-
tural losses caused by vertebrate pests in developing countries.
Specific objectives were as follows:

1. Establish the technical capabilities and support within govern-
ments and the agricultural sector to conduct programs in
vertebrate pest research and management.

2. Develop new and adapt existing practical low-cost methods and
technology to evaluate and reduce preharvest and postharvest
crop losses to vertebrate pests of significant regional
importance under local conditions.

3. Provide onsite training in research and management methods to
reduce losses by vertebrate pests.

4. Provide training at DWRC and appropriate universities to
perfect capabilities of counterparts to conduct programs in
vertebrate pest management.

HAITI

Breeding Biology of Village Weavers (Ploceus cucullatus)

Bird populations usually are lowest just before the reproductive
season. The annual production of young replenishes the number of
village weavers (Ploceus cucullatus) in Haiti, and because young
usually outnumber adults after the breeding season, the young cause
the greatest losses to grain crops in late summer and fall. In
years of poor reproduction, crop damage should be less; this seemed
to be the case in 1984.

Of ten colonies closely monitored in 1983, only five were occupied
in 1984 (Table 1). The number of active males in the colonies was
down about 70% in' 1984, and nests were about 80% fewer than in
1983. Thus, with fewer males, fewer nests, and fewer nests/male
(4.2 vs. 5.5) in 1984, undoubtedly, fewer young were produced.

Five of the colonies were located in acacia woodlands and five were
in inhabited areas on the outskirts of Port-au-Prince. In 1983,
the largest colonies were in acacia woodlands and accounted for 73%
of the nests. Only one woodland colony was active in 1984; it

contained only 7% of total nests and was deserted in mid-June.
Numbers of breeding village weavers were down in 1984 near
Port-au-Prince, and acacia woodland habitat did not support
colonies. These changes probably reflected a decrease in the
availability of food insects needed to sustain reproduction and
illustrated the potential for reducing both the population of
village weavers and the intensity of crop losses by limiting the
insect biomass available to sustain successful reproduction.

Table 1. Numbers of breeding males and nests in village weaver
(Ploceus cucullatus) colonies in Haiti.

In 1983, seven of the ten colonies formed early with nests being
built primarily in June. In the remaining three colonies, nests
were constructed in August and September. Adults had fledged their
young and departed by mid-August in early colonies and by
mid-October in late colonies. Old nests persisted for sometime in
trees; the rate of their disappearance was unknown. The disappear-
ance of 1983 nests in colonies was determined by periodically
counting remaining nests until May 1984 (Table 2). This disappear-
ance of nests varied considerably among colonies. A somewhat
steady disappearance of nests was seen at Airport, Shada N, Shada
SW, and Airport Pine, but the rate of loss was different. At most
other colonies, the rate of loss varied over time, while at Gas
Station no nests disappeared during the first 6 months. Rate of

Table 2. Disappearance rates for village weaver (Ploceus cucullatus) nests
observed in colonies in the vicinity of Port-au-Prince, Haiti; 1983/1984.

loss was related neither to the kinds of trees in which colonies
were located nor to the nest construction material. Results showed
that in some cases old nests can persist for almost 1 year. This
was not expected, but does clarify why many colonies with fresh
green nests often contained nests that looked much older.

Protecting Grain Sorghum From Birds

Bird damage to grain sorghum is serious and widespread in Haiti and
is the principal deterrent to the production of this crop. In the
past, sorghum fields matured at different times and were usually
destroyed by village weavers, locally known as Madame Sarah, and
yellow-faced grassquits (Tiarus olivacea). Farmers have reduced the
problem by coordinating planting time and growing tall,
photo-sensitive varieties that are not very productive but mature
at about the same time.

Bird-scaring reflection tape that had been used to prevent damage
in field trials in the United States, the Philippines, Bangladesh,
and Nepal, was twisted and stretched over the sorghum fields to
determine the effect on this situation. The method provided some
protection from birds for about 7-10 days, but birds gradually
became conditioned to the tape, and 25% sorghum was lost before
harvest.

In another attempt to repel birds, netting was suspended over
sorghum fields. This technique provided the most complete protec-
tion, but it is too expensive for use by Haitian farmers. However,
in crop research schemes, where losses to birds often interfere
with the collection of data and the interpretation of results, the
approach may be practical.

Protecting Corn From Woodpecker Damage

Developing corn ears on experimental plots at the Damien
Experimental Station have consistently suffered serious damage by
Hispaniolan woodpeckers (Melanerpes striatus) that puncture ears
and feed on the juices of the younger, growing ears. Between
February and December 1983, woodpecker damage was measured in five
experimental fields at Damien. Damage (expressed as the percentage
of ears damaged) ranged from 32.8% to 56.7%. Several wrapping
materials were identified in 1983 that successfully protected ears
and reduced woodpecker damage, but wrapping proved to be tedious
and expensive.

In 1984, red plastic strips (SaflagR), 5x20 cm, were split at one
end and attached onto the tip of young corn ears when woodpeckers
first began damaging fields. Strips were placed on only about 7%
of corn ears, but woodpecker damage was effectively reduced

In Haiti, "flagging" placed on maturing ears of corn
protects them from woodpecker damage.

throughout the fields. In January, for instance, woodpecker damage
was only 4.7% and 3.8% in two protected experimental fields.
Additional tests of this technique are needed. Red plastic strips
may help reduce woodpecker damage in corn, cacao, and other crops.

Small-farm Survey to Determine Rodent Activity

A small-farm survey was initiated on nine typical Haitian farms
with a mixed-cropping system in the Croix-des-Bouquets, Cul-de-Sac
Plain area, located 16-19 km northeast of the Vertebrate Pest
Laboratory at Damien, to evaluate vertebrate pest activity and
losses to agriculture. Three treatments were randomly assigned to
the farms and included rodenticide baiting, snap-trapping, and no
rodent control. One snap trap/100 m2 of cropland was set for a
minimum of 2 nights/month. One bait holder/1,000 m2 of cropland,
baited with 0.025% warfarin in coarse cornmeal was used. Bait
holders were checked weekly, and, if needed, additional bait was
added and holders were replaced. Rat activity was assessed 2
nights/month on all farms by tracking tiles.

The survey will be continued by Haitian scientists for several
months. After 1 year, the data will be analyzed to determine
vertebrate pest problems on small farms and provide potential
solutions.

Field Testing Bird-resistant Sorghum

A sorghum variety developed in Kenya, called Muvemba and thought to
be resistant to bird damage because of its high tannin content, was
no more resistant to bird damage than other varieties when grown at
the Damien Experiment Station. The Muvemba variety was planted
with three other varieties in small plots for seed multiplication.
Each variety was planted in four 5-m rows, adjacent to each other,
at the edge of a larger corn field. Village weavers fed in the
corn field and caused some damage to 35% of the corn ears. They
also fed in the small sorghum plantings and ate about 75% of the
seeds produced by each variety. Under these field conditions,
Muvemba sorghum was as susceptible to damage by village weavers as
the other varieties.

Cooperation With National and International Organizations

Communication and cooperation was maintained with district offices
of the Ministry of Agriculture throughout Haiti. In this way,
assistance and extension services were provided for the solution of
some vertebrate pest problems. The Port-au-Prince district
assisted in establishing our small-farm study in which crop losses
and damage prevention techniques were assessed on several peasant
farms in the Cul-de-Sac Plain.

Cooperation was continued with staff of Texas A&M University to
evaluate vertebrate pest damage levels and the effectiveness of
control techniques in experimental crops. At the Damien Experiment
Station, Texas A&M agronomists grow small grains throughout the
year. These crops suffer excessive damage during periods when few
other foods are available for rats and birds. This schedule
provides an excellent opportunity to evaluate crop protection
systems, because vertebrate pest damage is concentrated on the
small plots.

Personnel and Training

In late February, agronomists in Haiti participated in a Rice
Seminar at the Mauge Experimental Station in the Artibonite
Valley. In preparation for the seminar, numerous plantings of rice
were begun 3 months earlier to illustrate the influence of
different rice varieties, different planting dates, and different
rates of fertilizers and trace elements on growth characteristics
and yields. Jean-Paul Samedy used these rice plots to illustrate
methods for protecting rice from rats and birds. He presented a
paper describing the biology of these pests, the factors that
increase the probability of damage to crops, and data needed to
conduct effective vertebrate pest control.

On a typical multicrop small farm in Haiti the land is utilized to
grow corn, melons, sweet potatoes, and bananas during spring.

Based on the success of the multimedia "National Rat Control
Campaign in Wheat, 1982/83," a similar campaign was conducted
during the 1983/84 crop season to retain the level of motivation
for control activities by farmers. The preparation, organization,
and evaluation of the 1983/84 campaign involved staff of the
Department of Agricultural Extension (DAE) at the head office
(mainly the Vertebrate Pest Control Section of the Plant Protection
Programme) and in the field, Bangladesh-German Plant Protection
Programme and the Vertebrate Pest Research Laboratory (VPRL) of the
Bangladesh Agricultural Research Institute (BARI).

Total 1984 campaign costs were approximately US $36,000; $4,000
were contributed by the USAID-sponsored VPRL at BARI and the
remainder by the Bangladesh-German Plant Protection Programme. The
1983/84 campaign was organized like the previous campaign, taking
into account some of the recommendations that resulted from the
evaluation of the 1982/83 campaign, during which wheat farmers were
the major target group. In 1984, the campaign was expanded to
include all farmers during the winter crop season.

The evaluation of the campaign was done as follows:

1. A management monitoring survey was conducted late January to
monitor organization of campaign activities in the fields.

2. In March, just before wheat harvest, interview surveys and rat
damage assessments in farmers' wheat fields in 10 districts
were conducted by head office staff (Bangladesh-German Plant
Protection Programme and VPRL of BARI).

3. The farmer's opinion was surveyed by a team of independent
interviewers in nine districts. This" survey was concluded in
late April.

The campaign used all available mass media (radio, television,
newspapers, posters, instructional leaflets, training brochures)
and agricultural extension staff (Table 3). Posters, leaflets, and
brochures were distributed to all district headquarters by head
office staff from Dhaka. Agricultural extension staff then
distributed the material to upazila and union levels.

a Parts of this report have been extracted from a report by H.
Posamentier and A. Van Elsen, Bangladesh-German Plant Protection
Programme.

Table 3. Distribution of printed materials during the National Rat
Control Campaign, Bangladesh, 1983/84.

a Other organizations working with farmers and for use by head
office staff.

Part of the campaign was a rat tail collection competition. Prizes
were given to farmers, institutions such as schools, and staff for
collecting the most rat tails. The competition was advertised via
radio, newspapers, and instructional leaflets.

In 1983, approximately 80,000 ready-made bait packets were prepared
and distributed by the Bangladesh-German Plant Protection Programme
and the VPRL at BARI, while additional 140,000 packets were distrib-
uted by three private companies. In 1984, ready-made bait packets
were prepared and distributed by five private formulators only.
Bait packets (weighing 50 g) consisted of 2% zinc phosphide, crushed
rice, wheat flour, and soybean oil, were cut into sun-dried,
bisquit-size pieces and labeled with instructions for use and
precautions; they were sold for about 12/packet. According to
their reports, a total of 310,950 packets were distributed by
mid-February to the districts, but the amount received in each
district varied significantly from 35,000 packets received in
Rajshahi to only 200 packets received in Bandarban.

Field surveys and farmer interviews were conducted by staff of the
Bangladesh-German Plant Protection Programme and the VPRL at BARI.
Wheat fields were assessed for rat damage by using 10 sample
quadrats/field and counting all cut and uncut tillers in each
quadrat. For all plots, average damage of 2.45% cut tillers was
found (Table 4), and 68% of the plots showed evidence of rat
infestation (cut tillers or rat burrows).

In 1984, of 805 farmers interview, 40% carried out some kind of
control in the fields surveyed compared with 32% of 603 farmers

interviewed in 1983. The percentage of farmers using control
measures was higher in non-wheat-growing districts (45%) vs.
wheat-growing areas (39%).

In 1983, the ready-made bait was used far more widely than other
rodenticides (Table 5), and its use in 1984 in non-wheat-growing
districts increased sharply over that in 1983. The use of physical
or mechanical methods (digging, flooding, smoking, or trapping)
remained similar to those of the previous year and may, in fact,
not seriously compete with use of rodenticides but rather be an
additional activity. Ready-made bait was preferred over other
rodenticides; wheat farmers are the major users during this time of
the winter crop season.

Table 5. Control methods used in wheat fields during campaign,
Bangladesh, 1984.

Of all wheat fields, 18.8% were treated with ready-made baits (151
of 805 respondents). Projecting to a total of 4,250,000 wheat
fields in Bangladesh, approximately 797,000 were treated, indicating
that about 300,000-400,000 bait packets (one packet for two to three
fields) were sold to wheat farmers.

In 1984, damage reduction in fields treated with ready-made bait
vs. fields without control was only 41% compared to 56% in 1983
(Table 6). This may be due to an earlier onset of heavy rat
infestation and delays in the availability of the ready-made bait
after opening of the campaign.

Table 6. Comparison of control methods and rat damage to wheat,
Bangladesh, 1984.

a Not significant.
b Difference between locally
was significant at P <0.01.

available poison and ready-made bait

The approximate savings of wheat due to the use of ready-made baits
by farmers are given in Table 7. While the absolute amount in
monetary terms has risen from $480,000 to $720,000, the tonnage
saved relative to the total production has risen only slightly
(3.9% in 1983 to 4.1% in 1984). As in the previous campaign,
savings in other crops, particularly savings of stored foods in
villages and farmers' houses, must be added to the above figure.

A survey of farmers' opinions by interview was conducted. A total
of 1,089 farmers in 18 different upazilas of 9 districts were
interviewed, mostly while working in the field. Some of the data
are summarized in Table 8.

Table 7. Savings through the use of ready-made bait in standing
wheat in Bangladesh, 1983/84.

Tons

Total wheat production, 1983/84 1,314,000

Wheat production in rat-infested plots (68%) 893,500

Production in plots treated with ready-made bait
(30% of infested fields) 268,050

Loss at 4.90% (if no control) 13,134

Loss at 2.88% (if treated with ready-made bait) 7,720

Production saved through ready-made bait application 5,414

US $ saved through ready-made bait application
(at $136/ton) $736,304

During the 1983/84 national rat control campaign, a considerably
larger farmer population was reached. The proportion of farmers
who carried out rat control activities in their winter crops
increased substantially from 49% of those interviewed in 1983 to
67% in 1984. Control methods in 1984 changed little from 1983,
except for the use of rodenticides, which, in general, paralleled
the increase in number of farmers doing control.

The use of ready-made baits increased fivefold, both in number of
farmers who had seen the material in shops or the local market and
those that had purchased and used it. The distribution of 310,000
bait packets by mid-February and the continued supply, plus the
fact that the bait had been on the market for the past year,
undoubtedly led to many farmers being familiar with the product.
These results greatly exceeded expectations and more than met the
quantitative indicators for a successful campaign. The amount of
wheat saved, estimated from the reduction in rat damage in fields
where the ready-made baits were used, gave an 18:1 benefit:cost
ratio. This more than justified the efforts expended in this
national campaign.

The relative palatability of a new Imperial Chemical Industries
(ICI) brodifacoum wax block was compared with milled rice and wheat
seed. The three test foods were offered separately in three food
cups attached to the front of each cage. Six lesser bandicoot rats
(Bandicota bengalensis) were given this choice for 3 nights. The
position of the food cups was changed daily. One female rat ate
10.5 g of the 12.8 g of wax blocks consumed. None of the rats
died. Results are summarized in Table 9.

The acute oral LD50 of bromethalin for both sexes of B. bengalensis
using the Litchfield and Wilcoxon method was found to be 2.62 mg/kg
(95% CL 2.0-3.4 mg/kg). Results were similar to those for
bromethalin for Rattus norvegicus (LD50 = 2.01 mg/kg for females
and 2.46 mg/kg for males). In general, findings on the susceptibil-
ity of B. bengalensis to various toxicants have shown it to be
about the same as for R. norvegicus. The low LD50 of bromethalin
indicates it should perform well in the field.

Rat and Jackal Damage in Sugarcane

Three rat species, Rattus rattus, B. bengalensis, and Nesokia
indica, and the golden jackal (Canis aureus) cause damage to
sugarcane in Bangladesh. An intensive survey of vertebrate pest
damage in five sugarcane fields in the Sripur area was conducted at
the time of harvest in February. Three damage assessment methods
were evaluated: (1) cutting and pulling all stalks from two
randomly selected 5x5-m quadrats in each field. All stalks were
examined for jackal and rat damage, the number of internodes per
stalk were counted, and the number of jackal- and rat-damaged
internodes was recorded; (2) the same procedure was carried out on
two 2x2-m quadrats delimited by twine within each field, but without
cutting and removing the stalks; and (3) the same procedure was used
in an area delimited by attaching a 1.5-m long twine to a randomly
selected stalk and noting damage and total number of stalks falling
within the 1.5-m radius circle. No stalks were cut or removed using
this method; approximately four samples were taken per field. The
results of these assessment methods are summarized in Table 10.

There was good agreement among methods when assessing jackal damage,
but poor agreement when assessing rat damage. These results were
probably due to jackal damage being fairly uniform throughout the
fields, whereas rat damage was not uniform and damaged areas could
easily have been missed in the smaller quadrats (2x2 m, 1.5-m
radius).

The Agricultural and Economic Importance of the Golden Jackal in
Bangladesh

Farmers' perceptions of the agricultural and economic importance of
the golden jackal were determined by surveys of 11 representative
districts in Bangladesh. Farmers were interviewed individually by
staff of the VPRL at BARI, using a standard survey form. Informa-
tion sought included crops damaged by jackals, total crop value,
estimated value of crop losses, and the season when damage occurred.
Numbers and value of domestic animals killed by jackals within the
last year and the season when damage occurred were recorded. Inter-
viewers inquired whether a farmer made any attempts at jackal
control; what methods were used; when were jackals last seen or
heard; and whether the jackal population was increasing, decreasing,
or remaining about the same.

Rat damage to sugarcane at harvest time (above) and golden jackal
damage to sugarcane (below) in fields in the Sripur area,
Bangladesh.
22

Of the 1,110 farmers interviewed, a total of 760 (68.5%) farmers
reported problems with jackals, 286 (25.8%) reported damage to
field crops, and 693 (62.4%) had lost domestic animals. The
average farm income in Bangladesh is less than US $100. Total crop
losses of those surveyed were estimated as US $10,145.60, or an
average of $8.88/farmer for all farmers in the sample. The annual
losses of domestic animals averaged $7.24/farmer. Aggregate losses
for both field crops and domestic animals were $16.12/farmer.
Extrapolating this to the 12 million farmers in Bangladesh would
give an estimated $193 million lost annually due to jackal damage
to crops and domestic animals. This ranks jackals second only to
rats and mice as vertebrate pests of agriculture in Bangladesh.

Sugarcane was the field crop reported as most frequently damaged.
Jackal damage to sugarcane stalks is more severe than rat damage;
almost invariably the stalk is killed due to jackals crushing the
intermodal areas between their jaws. Damage starts in July and
continues until harvest in December/January. Watermelons and musk
melons ranked next in frequency of reports. Farmers must guard
their fields at night for 2 months while the melons ripen to
minimize jackal damage. Jackals also attacked and damaged
pineapple, jackfruit, maize, groundnuts, cucumbers, sweet potatoes,
potatoes, gourds, and eggplant. Some crops, such as rice, jute,
and wheat are accidentally damaged when jackals run, dig, or forage
in these fields.

Concerning domestic animals, 589 farmers reported 4,223 chickens as
killed by jackals, 231 farmers reported losses of 521 goats, and
162 farmers lost 632 ducks. A few reports were received of losses
of pigs (9), cattle (5), pigeons (4), freshwater prawns (2), and
sheep (1). Predation on chickens and goats was most intense in the
months of May, June, July, and August.

Very few farmers have the resources or knowledge to protect their
fields from damage by jackals. Only 42 (3.8%) reported doing any
jackal control; the method most often used was chasing the jackals
and killing them with sticks. Another method reported was guarding
the fields at night.

Farmers were asked when they had last seen or heard jackals around
their houses or village. In 1,072 replies, 616 (57.5%) had seen or
heard jackals the night before, and 204 (19.0%) replied "sometime
within the past week." Only 158 (14.7%) had neither teen nor heard
jackals in their area for 1 month or longer. Some of these replies
were from areas where monsoon rains had apparently driven jackals
out to the nearest large areas of higher ground, leaving the
smaller island areas devoid of jackals for the flood period.
Jackal presence was reported, however, by one or more farmers in
every village (220 surveyed) in each of the 11 districts.

Bangladeshi farmer is being interviewed by M. D. Haque, Vertebrate
Pest Research Laboratory, BARI, to determine the agricultural and
economic importance of the golden jackal.

24

/1

The jackal is an opportunistic omnivore, intelligent, wily, and
resourceful, yet well conditioned to the presence of man. The
jackal seems to have successfully adapted to the densely populated,
intensively cultivated agro-ecosystems of Bangladesh. Jackal
control to reduce crop damage would seem to be justified in field
crops such as sugarcane, melons, pineapple, and maize.

Bait Development for Jackals

The Vertebrate Pest Research Laboratory tested several baits to
determine which, if any, would be preferred by the golden jackal.
Several foods were offered to three caged jackals. All test foods
were mixed with boiled rice, except beef fat and tallow. Jackals
preferred raw chopped chicken and selected it as their first food to
be eaten in 22 (73%) of 30 offerings. Beef tallow was the second
choice, followed by raw egg, chopped shrimp, and beef fat. A bait
consisting of beef tallow and chopped, cooked chicken molded into
40-g bait cubes was readily accepted by caged jackals.

Pest birds pull wheat sprouts shortly after emergence and can cause
a loss of 40 to 50% of the sprouts in farmers' fields. This can
result in a yield reduction of 17 to 18%. Damage is caused primar-
ily by pied mynas (Sturnus contra), common mynas (Acridotheres
tristis), pigeons (Columba livia) and jungle crows (Corvus
macrorhynchos). Chemical repellents applied to the wheat seed just
before sowing can be used to reduce sprout loss to pest birds.

A field trial using a common fungicide, copper oxychloride, as a
bird repellent on sprouting wheat was conducted in Gazaria
Upazila. Ten fields were sown with Sonalika variety wheat seed
treated with 1.25% copper oxychloride, and 10 fields were sown with
the same variety wheat seed treated with 1.25% chalk powder. Chalk
powder and copper oxychloride showed no effect on germination rate,
which was 98-99%. The chalk powder was used as a reference, since
all farmers demanded some chemical treatment for bird control.

Just before harvest, panicles were clipped from 10, 50x100-cm
quadrats in each field. Panicles were counted, mechanically
threshed after sun-drying, and weighed to the nearest gram. Yield
data and panicle counts are shown in Table 11. Six fields (two
treated and four reference) had already been harvested by the
farmers, therefore, were not available for sampling. A t-test
comparison of the mean differences, either panicle counts or yield,
showed no significant differences between the treatments. Results
of this test showed that copper oxychloride did not repel birds
from feeding on sprouting wheat.

Common mynas (Acridotheres tristis) are responsible for losses to
drying grain in village situations throughout Bangladesh.

A study to determine simulated bird damage to sprouting wheat (20
days after sowing) utilizing a randomized block design was conducted
in Gazaria Upazila on a 13.5x21-m experimental area. The study
plot was divided into four blocks; each block was divided into 7
plots for a total of 28 plots. Each plot measured 2x2 m and was
separated by pathways 0.5 m wide. The plots were marked with
bamboo sticks and numbered tags. The experiment consisted of four
replications with seven damage intensities--0%, reference; 5, 10,
15, 20, 30 and 40% sprout removal.

Within each plot, plants were counted and a fixed number (800/plot)
was retained. Then the appropriate percentage of sprouts was
randomly removed as simulated bird damage.

The Sonalika wheat variety was sown at the rate of 60 kg/ha on 19
December 1983; sprouts were removed on 12 January 1984 to meet the
required counts. Plots were fertilized and weeded. Rodent control
was done in adjacent fields to prevent rat damage. The entire field
was covered with a bird net during the sprouting period to prevent
bird damage. Individual plots were harvested on 25 March 1984, 98
days after sowing. Panicles were tied into bundles and marked.
Bundles were spread individually to sun-dry and were then mechani-
cally threshed. Panicles in each plot were counted and the yield
of each plot was weighed to the nearest 0.1 g. Statistical analysis
was done with analysis of variance. Results are shown in Table 12.

Table 12. Mean number of wheat panicles and wheat yield at
different levels of simulated bird damage,
Gazaria Upazila, Bangladesh.

The experiment showed a definite trend in decreasing panicle counts
with increasing sprout removal (r = 0.42707). The yield weights of
the same samples, however, showed no such correlation. Analysis of
variance showed no significant differences between blocks or
treatments. Because panicle counts vs. treatment showed a declining
trend relationship, it was suspected that yield samples might have
been intermixed or mislabeled either before or after mechanical
threshing. The experiment will be repeated under similar
conditions.

Myna Damage to Wheat Seedlings in the Aviary

Two aviary trials were conducted to determine the effectiveness of
methiocarb and copper oxychloride treatments to wheat seed. Sprouts
of chemically treated wheat seeds were exposed in pots to 10 mynas
(6 A. tristis and 4 A. fuscus). Wheat seeds were treated with
0.25% methiocarb or 1.25% copper oxychloride and sown at a rate of
100 seeds/pot; untreated seeds served as reference. Pots were
repositioned daily. Germinating seeds were counted during the
first 4 days, and damage was assessed by counting the number of
seedlings remaining 10 days after sowing. In the first trial,
methiocarb gave better protection; in the second trial, copper
oxychloride excelled. However, there was less damage overall in
the second trial, probably due to the same birds being again
exposed to the same repellents. Results are given in Table 13.

Table 13. Percent of wheat sprouts removed by mynas after seeds had
been treated with chemical repellents, Bangladesh.

% damage
Copper
Trial Replication Reference oxychloride Methiocarb

I 1 79 58 30
2 60 20 25
3 78 40 34
4 66 54 23
Avg 70.8 43.0 28.0

II 1 51 16 24
2 35 14 26
3 48 13 28
4 49 22 32
Avg 45.7 16.2 27.5

Avg both trials 58.2 29.6 27.7

Bird-scaring Reflection Tape as a Bird Repellent in Maturing Oilseed
and Grain Crops

The traditional method used in Bangladesh to minimize bird damage
is to employ a bird scarer who patrols the field and frightens the
birds by shouting and making loud noises. Another method is to use
fluttering pieces of cloth or pieces of plastic sheet on bamboo
sticks placed in the field.

Bird-scaring reflection tape was evaluated to determine its
effectiveness in repelling birds from maturing crops. The tape was
silver on one side and red on the other. It reflected sunlight to
produce a flashing effect, and when stretched, it pulsated and
produced a loud, humming, or sometimes thunder-like noise in the
wind. Reflection tapes were installed over fields of sunflowers,
maize, and millet. The tape was strung in parallel rows across the
plots, just above the crop and slightly twisted.

Field trials are conducted in Bangladesh to evaluate bird-scaring
reflection tape.

31

Rose-ringed parakeets had eaten 23% of all sunflower seeds in the
trial plot at Jessore when we installed reflection tape in late
March. Before the tape was installed, an average of 12 parakeets
and 6 sparrows fed per observation. Birds fed regularly throughout
the day but numbers peaked during early morning and late afternoon.
For 15 days after the tape was installed, virtually no parakeets
entered the plot and damage ceased. Several sparrows occasionally
reentered the plot, flying in beneath the ribbon to feed on seed on
the ground. The flock of 18-25 parakeets remained in the area,
loafing in palms surrounding the sunflowers. They often approached
the sunflowers, but always returned to the trees, then fed in wheat
stubble in an adjacent field. This effect was striking because
parakeets generally are difficult to repel from sunflowers,
especially after they establish feeding patterns.

In the trial to try to repel a resident population of 100-200 munias
from plots of foxtail millet, the reflection tape caused birds to
move between taped and untaped plots. This change occurred almost
immediately each time the tape was moved. The morning the trial
began (30 March), an average of 15 birds/count were feeding in Plot
1. For 4 days after the tape was installed, no birds fed in the
plot, but 20-24 birds/count fed in Plot 2. At noon on 3 April, the
tapes were switched to Plot 2, and birds immediately began feeding
in Plot 1. However, on 8 April when both plots were covered with
tapes, munias fed in both plots, reaching a peak of 60 birds/count
in Plot 2 and 35 birds/count in Plot 1. These results suggested
that reflection tape can repel munias from individual millet fields
if an alternative food is available.

In the third trial at Jessore, parakeets avoided a maize plot with
tape and fed elsewhere. A total of 8 parakeets and 70 other birds
(mynas and sparrows) were counted during 150 observations over 15
days in the plot with tape; 111 parakeets and 507 other birds were
counted in the untaped plot during the same time period.

Reflection tape also reduced damage to maize by jungle crows in a
study at BARI, Joydebpur. An additional 5.3% damage occurred in
one plot after tape was installed compared to a 9.9% increase in an
unprotected plot. The number of birds counted feeding in the taped
plot decreased 83% from preinstallation counts.

Cooperation With National and International Organizations

The VPRL cooperated with the Directorate of Agricultural Extension
Services and the Bangladesh-German Plant Protection Programme in
planning, implementing, and funding the National Rat Control
Campaign in Wheat in Bangladesh.

At the request of Mr. John Conway, Pest Infestation Control
Specialist, Ministry of Food, laboratory evaluations of a
paraffin-block anticoagulant bait were done at VPRL.

Technical advice, traps, and rodenticide baits were provided to the
British Overseas Development Agency, Bangladesh Rice Research
Institute (BRRI), to protect experimental deepwater rice plots and
to the Diabetes Hospital, Dhaka, in an attempt to control rats that
were damaging electrical cables on X-ray equipment.

Studies of rodent populations in farmers' houses continued as part
of a cooperative effort with the Food and Agriculture Organization
(FAO)/BRRI project on postharvest storage losses of paddy at the
farm and village level.

During a visit at the Seventh Day Adventist Seminary School at
Monosapara, Netrakona District, technical advice, traps, and
rodenticides were provided. The school was experiencing severe
problems with porcupine damage in their pineapple gardens. Baiting
with coumatetralyl concentrate mixed with cubed, ripe pineapple
stopped the damage within a few weeks.

Personnel and Training

Mrs. Parvin Sultana continued her postgraduate studies in Inter-
national Vertebrate Pest Management at Colorado State University,
Ft. Collins, Colorado. Mrs. Sultana will complete her studies in
September 1985.

Mr. Shahabuddin Ahmad was chosen to work on an M.S. degree in
Economic Ornithology. The university will be selected at a later
date.

In September 1984, Mr. Rajat K. Pandit enrolled in an M.S. degree
program in Agriculture (Entomology) with Bangladesh Agricultural
University. He is taking classes at the Institute of Postgraduate
Studies in Agriculture at Salna, Gazipur. Mr. Pandit's research
topic is "The Biology and Ecology of Rattus rattus in the Gazipur
District, Bangladesh."

In November 1984, Mr. Emdadul Haque enrolled in a Ph.D. program in
Zoology at Dhaka University. His research topic is "The Biology
and Ecology of the Short-tailed Mole Rat, Nesokia indica, in
Bangladesh."

Radio Broadcasts: Five-minute radio talks on various pest manage-
ment topics were broadcast in Bengali language on the Bangladesh
Broadcasting System by all counterpart staff of the VPRL.

Mr. M. E. Haque Insect problems and control in coconut.
Insect problems and control in pomegranate.
Rat problems and control in deepwater rice.

Dr. M. A. Karim

Rat problems and control in stored grains.
General review of rat problems and their
control in Bangladesh food crops.

Mr. Shahabuddin Ahmad Pest bird problems and control in maize.

Mr. M. Y. Mian

Mr. R. K. Pandit

Rat problems in stored foods and their
control.

Vertebrate pest problems in field crops and
their control.

Vertebrate Pest Seminars: Half-day seminars on vertebrate pest
problems and control, illustrated with color slides and narrative,
were given at BARI regional (RARS) and subregional (SubRARS)
Agricultural Research Stations, to personnel of the Thana Training
and Development Center (TTDC), and to students and training staff
at Agricultural Extension Training Institutes (AETI) from September
through December (Table 14).

During 1984, DWRC staff traveled in Asia, the Caribbean, Latin
America, Africa, and Europe in conjunction with ongoing field
research activities and at the request of FAO and foreign govern-
ments through USAID Missions or USAID Washington, to assess verte-
brate pest problems, review, evaluate, and coordinate present and
future research programs, and present seminars. TDY activities from
DWRC have become an increasingly important part of the project and
DWRC will continue to respond to such requests through USAID. Many
types of short-term evaluations and cooperative studies with
host-country scientists may be carried out expeditiously in this
manner. This travel involved 411 man-days in the following
countries:

Travel dates, persons involved, countries visited, and the purpose
of each trip are outlined briefly in Table 15. Detailed information
is contained in individual trip reports on file at the Section of
International Programs, DWRC.

An important function of the Section of International Programs is
to provide assistance to many countries and international organiza-
tions. During 1984, 184 requests from 63 countries were received
and answered (Table 16).

Table 15.

International travel for technical assistance projects by USAID/USFWS-DWRC personnel
during 1984.

At the request of National Parks and
Wildlife Management Department, assist
in evaluating trimethacarb as a bird
repellent to maturing wheat.

Set up laboratory and capture animals
for training purposes.

Discuss vertebrate pest damage problems
in agricultural crops on the mainland of
Equador and the Galapagos Islands with
USAID/Quito personnel. Recommend methods
for feral animal control. Honduras:
Recommend bird and rodent control methods
in rice and corn.

Improved maize drying cribs are being evaluated by USAID-sponsored
storage project personnel in Kenya. These cribs are intended to
permit early harvesting and reduce rodent infestation.

40

AFRICA

Cooperative Research

Since the closure of the USAID/DWRC Vertebrate Pest Project in
Sudan in 1981, USAID/DWRC research activities on bird pest problems
in Africa have been extremely curtailed. Our program consisted of
laboratory work on evaluating less susceptible sorghum varieties,
sensory cues to enhance methiocarb efficacy, trimethacarb field
trials, and trace element analyses. A bird-scaring reflection tape
study was conducted in Zimbabwe. DWRC's collaborative work with
the Eastern Africa Quelea Project has been limited to supplying
materials for aerial application of fluorescent particle markers,
cooperating in repellent and tape studies, training, and planning a
book and Experts' Consultation on quelea.

"Ecology and Management of the Red-billed Quelea"

This book will bring together much of the research, management, and
training aspects of quelea work conducted during the past 20
years. Approximately 75% of the chapters are drafted and being
reviewed. DWRC and FAO personnel are editing the book which will
be published by Oxford University Press.

PROBLEM DEFINITION

Pakistan

During the last 2 years, DWRC biologists have assisted the Govern-
ment of Pakistan in planning a vertebrate pest control project for
possible implementation under the USAID/Pakistan-sponsored
Agriculture Production, Distribution, and Storage (APDS) Project.
In 1984, a DWRC biologist assisted in preparation of a scope of
work document for these activities in the APDS Project.

Nepal

At the request of USAID/Nepal, DWRC helped the Government of Nepal
survey rodent and bird damage in agriculture, assess alternative
research and extension approaches to vertebrate pest control on
small farms, and outline the requirements for implementing verte-
brate pest management programs. Two seminars were presented to
faculty and students at the Institute of Agricultural and Animal
Sciences at Rampur.

Rodent Control in the Maldives, Indian Ocean

At the request of the Government of the Republic of the Maldives,
FAO funded a DWRC consultant to evaluate rodent pest problems in
coconut and recommend methods to reduce coconut losses to rodents.
The Republic of the Maldives, with about 1,000 major islands, is a

AFRICA

Cooperative Research

Since the closure of the USAID/DWRC Vertebrate Pest Project in
Sudan in 1981, USAID/DWRC research activities on bird pest problems
in Africa have been extremely curtailed. Our program consisted of
laboratory work on evaluating less susceptible sorghum varieties,
sensory cues to enhance methiocarb efficacy, trimethacarb field
trials, and trace element analyses. A bird-scaring reflection tape
study was conducted in Zimbabwe. DWRC's collaborative work with
the Eastern Africa Quelea Project has been limited to supplying
materials for aerial application of fluorescent particle markers,
cooperating in repellent and tape studies, training, and planning a
book and Experts' Consultation on quelea.

"Ecology and Management of the Red-billed Quelea"

This book will bring together much of the research, management, and
training aspects of quelea work conducted during the past 20
years. Approximately 75% of the chapters are drafted and being
reviewed. DWRC and FAO personnel are editing the book which will
be published by Oxford University Press.

PROBLEM DEFINITION

Pakistan

During the last 2 years, DWRC biologists have assisted the Govern-
ment of Pakistan in planning a vertebrate pest control project for
possible implementation under the USAID/Pakistan-sponsored
Agriculture Production, Distribution, and Storage (APDS) Project.
In 1984, a DWRC biologist assisted in preparation of a scope of
work document for these activities in the APDS Project.

Nepal

At the request of USAID/Nepal, DWRC helped the Government of Nepal
survey rodent and bird damage in agriculture, assess alternative
research and extension approaches to vertebrate pest control on
small farms, and outline the requirements for implementing verte-
brate pest management programs. Two seminars were presented to
faculty and students at the Institute of Agricultural and Animal
Sciences at Rampur.

Rodent Control in the Maldives, Indian Ocean

At the request of the Government of the Republic of the Maldives,
FAO funded a DWRC consultant to evaluate rodent pest problems in
coconut and recommend methods to reduce coconut losses to rodents.
The Republic of the Maldives, with about 1,000 major islands, is a

M4144itM
*,,y%~-

During bait consumption comparison tests in the Maldives, baits were
placed under a woven coconut frond roof to protect them from rain.

country dependent mostly on fish from the sea and coconuts from the
land. Most coconut stands are not well maintained. Yields are
low, with estimates ranging from 5 to 11 nuts/palm/year. Because
nuts are small, seven nuts are needed to produce 1 kg of copra as
compared to four nuts for 1 kg of copra in the Philippines.

Rattus rattus has been damaging coconuts in the Maldives since at
least 1602. Damage estimates range from "severe" to more quantified
estimates "as high as 40-50% of harvest." Only 50% of domestic
coconut needs are met because of a decreasing number of coconut
trees and an increasing human population. For this reason, FAO
requested DWRC to evaluate the rodent problem, design a rat control
program, and conduct preliminary training within the Ministry of
Agriculture.

Rat activity and bait acceptance were determined (Tables 17 and 18)
using tracking tiles and snap traps in coconut stands and village
habitat. Low rat activity occurred in coconut stands compared with
villages. However, during the day rats were readily observed in
the coconut canopy; damaged, fallen nuts were seen, indicating an
arboreal preference in coconut by rats.

Table 18. Bait consumption comparison tests (paired
choice), Kuramathi Island, Alifu Atoll,
Maldives, April 1984. Between 1800 and 0600 on
the day of the test, bait was placed in a
plastic petri dish under a woven coconut frond
roof.

While snap-trapping in Male, the capital, a previously unreported
commensal rodent, Rattus norvegicus, was caught. This species
probably came to the island with imported goods regularly shipped
from Colombo, Sri Lanka, or Singapore, or was introduced from a
former Air Force base in a southern Atoll.

Status of Rodent Problems in East Africa

The FAO requested a DWRC consultant to evaluate rodent pest prob-
lems in Ethiopia, Somalia, Kenya, Tanzania, and Zimbabwe. Rodents
cause significant crop damage throughout East Africa. The unstriped
grass rat (Arvicanthis sp.) is common in East Africa from Tanzania
north to the sub-Sahara region. It prefers savannah grassland and
a herbivorous diet of grasses, inducing wheat, barley, maize,
sorghum, and teff. The multimammate rat (Praomys natalensis) is
associated with human settlements throughout Africa. It is a true

omnivore and consumes a variety of crops planted near villages as
well as stored foods. This rat can transmit plague to humans via
infected fleas. Under favorable conditions, the rat's mobility and
high reproductive potential result in rapid population increases.

These two rats are responsible for the rodent "outbreaks" that
periodically occur in East Africa. These outbreaks are usually
associated with above-normal rainfall or rains that occur after a
prolonged drought. Most countries have a rodent or vertebrate pest
control unit within the Ministry of Agriculture, but the magnitude
of these outbreaks usually overwhelms control efforts. A rodent
monitoring and forecasting program, based on available and
additional research results, would be extremely helpful to East
African agriculture.

Several other rodent species can cause severe damage locally (Table
19). Grass mice such as Rhabdomys pumilio or Lemniscomys striatus
and fossorial mole-rats (Tachyroryctes splendens) are frequently
involved in field crop damage. The cane rat (Thryonomys
swinderianus) damages crops cultivated near swampy or moist
lowlands. Commensal rodents such as the brown rat (R. norvegicus),
roof or ship rat (R. rattus), and house mouse (Mus musculus) are
present. R. norvegicus is primarily restricted to the larger port
cities; R. rattus is expanding its range in East Africa and is
competing with P. natalensis as a common household pest. Gerbils
(Tatera spp.) and some ground squirrels such as Xerus rutilis are
present throughout East Africa and are particu- larly damaging to
seeds at planting time. The crested porcupine (Hystrix cristata)
damages any cultivated root crop and mature maize.

Control methods presently used include chemical baiting, a variety
of physical methods including flooding or digging of burrows, and,
to a much lesser extent, biological control such as weeding to
reduce shelter for rats. Rodenticides being used include zinc phos-
phide mixed with cereal grain and, less frequently, anticoagulants.
Laboratory and field efficacy trials are lacking for most chemicals
and rodent species.

Ethiopia, Somalia, Kenya, and Tanzania have reported severe rodent
pest damage. Ethiopia has been very active in conducting field
surveys, experiments, remedial control projects, and training. Most
other countries need to increase or strengthen support of their
rodent control programs. With support from international organiza-
tions, rodent control programs can be strengthened in East Africa.

At the request of USAID/Quito, a DWRC biologist evaluated verte-
brate pest problems in Ecuador on the mainland and the Galapagos
Islands. Rodents and birds damage several agricultural crops on the
mainland (Table 21), however, little detailed information is
available. Damage to agricultural crops also occurs in the
Galapagos, but hectarage involved is small (<1% of the agricul-
tural lands of Ecuador). On Isla Isabela, rat damage to pineapple,
papaya, banana, sugarcane, and Citrus spp. was reported.

During the last 3 years, the dark-rumped petrel colony on Isla
Floreana has made a remarkable comeback after a rat control project
was initiated. Annual nesting success has increased from about 30%
in 1982 to over 70% in 1984. A similar effort is being organized
in a threatened petrel colony on Isla Santiago. DWRC will continue
to provide guidance for this project which is conducted and
supported by the Charles Darwin Research Station.

The iguana, one of many rare, endangered species on the Galapagos
Islands, is preyed upon by feral dogs and cats.

While snap-trapping rodents in Puerto Ayora, Isla Santa Cruz,
several Norway rats (R. norvegicus), previously unreported, were
caught. This rat was probably introduced from the mainland by
ships that anchor in Academy Bay and off-load goods to smaller boats
that dock in Puerto Ayora and have no quarantine restrictions.
Although presently restricted to urban areas, the Norway rat poses
a potential threat to native species if it extends its range.
Tourist and fishing boats that anchor near islands currently free
of introduced commensal rats, threaten remnant native rodent
populations such as Oryzomys baurus, which is only found on Isla
Santa Fe. If R. norvegicus and R. rattus are introduced to Isla
Santa Fe, 0. baurus may become extTnct.

Improved Grain Storage and Pest Control in El Salvador: Evaluation
and Recommendations

The Food and Feed Grain Institute (FFGI), Kansas State University,
and DWRC cooperated in an evaluation of grain storage and pest
control problems in El Salvador. Engineering problems associated
with transport and storage of cereal grains and vertebrate pest
problems were evaluated.

Preharvest losses to vertebrate pesis are at least as serious as
losses in stored grain. Rodent infestations are periodically a
serious problem in rice, sugarcane, and corn. The taltuza
(Pappogeomys spp.), a large pocket gopher, burrows under growing
crops and destroys the roots; granivorous birds cause serious

g1!

Grain sacks are often stored in the open which makes them more
susceptible to rodent damage.

Presently, the Centro Nacional de Tecnologia Agropecuaria (CENTA) is
involved in vertebrate pest control in El Salvador. The DWRC
specialist recommended several methods to control vertebrate pests
in the field and in storage situations. However, preliminary
research is necessary to determine major pest species, extent and
nature of damage, and habitat conditions.

The solutions proposed for improving grain handling and storage
techniques included: on-farm grain-drying procedures, dissemina-
tion of technical information to farmers through an extension pro-
gram, price modification for grain purchased by the Institute
Regulador de Abastecimientos (IRA), the reconstruction of IRA grain
facilities, and the implementation of a solar drying program.
In-country training by DWRC specialists was suggested for IRA and
CENTA personnel as well as for private grain buyers and processors.
University studies for CENTA specialists were also suggested.

To obtain LD50 values, trimethacarb and methiocarb were either sus-
pended or dissolved in propylene glycol and dosed by oral gavage.
Values of Lonchura spp. were close when treated with methiocarb and
showed approximately twice the toxicity of P. montanus (Table 22).
Trials with trimethacarb showed that L. punctulata and L. malacca
had similar LD50 values (4.16 and 3.13 mg/kg, respectiveTy), while
L. leucogaster and P. montanus showed much less toxicity (23.01 and
73.93 mg/kg, respectively).

During R50 trials, repellency values for trimethacarb were similar
for the three Lonchura spp. The R50 values for both chemicals
indicated a potential for protecting maturing crops from Lonchura
spp. damage. Repellency values for P. montanus will be determined
at a later date. Also, laboratory Trials with copper oxychloride
will be conducted as well as cage studies with all three avicides
utilizing maturing potted rice and sorghum plants and individual or
grouped species of birds.

Table 22. Toxicity and
trimethacarb
Philippines.

repellency values for mnethiocarb and
tested on bird pest species in the

Because of growing recognition of the importance of vertebrate pests
to food production and storage in most countries of the world, there
is an increasing need for specialists to define, research, and
manage these problem species. Recognizing the need for graduate
training in the newly emerging field of Vertebrate Pest Management
(VPM), the Department of Fishery and Wildlife Biology, Colorado
State University (CSU), has developed a cooperative arrangement with
the U.S. Fish and Wildlife Service's Denver Wildlife Research Center
for individuals seeking advanced education in Vertebrate Pest
Management and fields related to the control of animal damage. A
special effort has been made to address the individual needs of
international participants in managing vertebrate pest problems in
their home countries. This effort supplements programs presently
existing at other universities.

The graduate research may be conducted at Colorado State
University, at the Denver Wildlife Research Center, or at various
cooperating field stations in the United States or other

countries. In the latter cases, a research scientist at the field
station, who also is an appointed CSU affiliate faculty, will be
designated to supervise the student's progress. Prospective
students engaged in rodent or bird control operations or related
research in VPM in tropical countries are urged to consider this
offering for specialized graduate education. Programs lead to the
master of science or doctor of philosophy degrees.

During the 4 years this program has existed, 37 students, including
individuals from Bangladesh, Colombia, Ethiopia, Guatemala, Malawi,
Nicaragua, Nigeria, Sudan, and Venezuela have enrolled. Several of
these students have completed or are in the process of completing
advanced degrees in a variety of topics relating to bird hazards to
aircraft, bird pests in Bangladesh, vertebrate pests of Venezuela,
and wildlife management in Sudan.

For additional information including the General Catalog, Inter-
national Student Information Brochure, and detailed application
procedures, contact:

DWRC also continued to assist graduate student researchers in
Vertebrate Pest Management at Bowling Green State University, at
the University of California at Davis, at North Carolina State
University, and at the University of the Philippines at Los Banos.
The program at Bowling Green State University will place less
emphasis on training of foreign students due to Dr. William B.
Jackson's retirement in December 1984. Some candidates for
advanced degrees visited DWRC during the year or conducted their
research under the guidance of DWRC biologists.

SUPPORTING RESEARCH

Profiling, Mimicking, and Masking the Flavor of a Selected
Rodenticide

Rodenticide baiting frequently becomes ineffective with certain
relatively fast-acting toxicants such as strychnine. This problem
occurs when rodents detect the flavor of strychnine in the bait
after being adapted to the flavor of untreated food during a pre-
baiting period. At this point, rodents ingest a very small amount
of the adulterated food, receive sublethal toxic effects, and show
extreme bait avoidance based on a conditioned flavor aversion. This
essentially nullifies further control efforts. To reduce this
impediment to rodenticide baiting, research was conducted to mimic
or mask rodenticide flavors in order to counteract the flavor
aversion effect.

Various methods have been used to gather information on the per-
ceived taste qualities of materials to nonhuman species. One method
is to teach an animal a specific response to one tastant and test
for its generalization of that response to another. This procedure
demonstrates that rats (Sprague Dawley-derived Rattus norvegicus)
and hamsters (Mesocricetus auratus) tend to categorize tastants
into four groups. By analogy to humans, these groups are called
sweet, sour, salty, and bitter. In our experiments, a similar
procedure was used, but for a different purpose. The aim was to
determine whether generalization could be used to profile flavor
components of strychnine, a rodenticide with known bait-aversion
problems.

In Experiment 1, rats drank a small amount of strychnine solution
and were then given an injection of lithium chloride (LiCl) to
generate nonlethal toxicosis. Generalization of learned strychnine
taste aversion to four nontoxic flavors was then assessed in the
animals. Additional conditioning and generalization trials followed
until 24 flavors had been presented. In Experiment 2, rats were
conditioned to avoid individual flavors or strychnine flavor mimics
blended according to the amount of generalized aversion observed in
Experiment 1. Tests were then given for generalization of learned
aversion from the simple flavors to the mixtures, from the mixtures
to the simple flavors, and from either to strychnine. In Experiment
3, two concentrations of sodium chloride (NaCI) were mixed with
strychnine or one of the flavors, sucrose octaacetate (SOA), used in
previous experiments. These stimuli, as well as SOA alone, strych-
nine alone, and each of the NaCl concentrations, were presented to
rats during conditioning. As in previous experiments, generaliza-
tion followed. In Experiment 1, learned strychnine aversion gener-
alized to the simple, bitter flavors (P <0.01). In Experiment 2,

aversion to flavor mixture mimics generalized more strongly to
strychnine than learned aversion to simple flavors (P <0.01). In
Experiment 3, NaCl masked or otherwise suppressed the bitter flavor
of strychnine or SOA, insofar as no groups conditioned with a
bitter-salt mixture generalized aversion to the bitter flavor alone
(P <0.01).

Results showed that rats are capable of recognizing the flavor
components of strychnine. Moreover, when these components are
mixed in proportion to the degree of generalized aversion, a mimic
of strychnine is obtained. Although these results are from
laboratory tests, we believe that the methods can be effectively
applied in the field to improve baiting efficacy.

Development of Radio Control Cannon Net Trigger

A digitally encoded radio control was developed to remotely trigger
cannon nets for capturing birds. This prototype circuit can be
programed with about 32,000 unique code combinations to prevent
false triggering by extraneous signals. During a field demonstra-
tion, the remote control successfully triggered cannon net squibs
at a distance of about 1.6 km. This distance exceeded the intended
range for such a system and met the design criteria.

In a previous study of small mammals in farm and village housing,
we estimated an average of 3.0 rodents/structure and the annual
losses of stored paddy (raw, unhusked rice) as 53 kg/household.
This study underestimated both the rodent populations and the
losses of stored foods because rat activity and trapping was only
measured on the floor inside the houses. Tracking tiles, used to
measure animals activity, and traps were given to the householder
to place, and they invariably set them on the floor. Later
observations made by placing tracking tiles on shelves, platforms,
lofts (machas), and in paddy storage containers (doles) confirmed
that about 70% of the small-mammal activity in farmers' houses
takes place off the floor.

A redesigned study was initiated in June 1984 to more accurately
assess small-mammal activity and population estimates from trapping
data by placing tracking tiles and traps on the floor, on platforms,
and in storage baskets. Village sites in a deepwater, rice-growing
area in Mirzapur Upazila, Tangail District, were selected for study.
Each month, tracking tiles were set one night, traps the next 3
nights, followed by another night of tracking tiles in 20 houses.
The presence or absence of rat burrows in each house was recorded,
also the farmer's estimate of the quantity of stored paddy in his
house.

Results of tracking tile activity, animals captured, and estimated
small-mammal populations are summarized in Table 23. The
small-mammal populations were estimated by the change in proportion
of tracking tile activity due to the removal of the small mammals
during the 3 nights of trapping. Because toads were captured in
rat traps, their captures were included in the overall population
estimates, but their numbers were deducted to give the small-mammal
estimates. The estimated small-mammal populations ranged from 72
to 552 per month during the 7-month period of this study.

Table 24 lists the animal species captured monthly. House mice
remain by far the most prominent of the rodent species in farmers'
houses. However, we now know that trapping results underestimate
rat populations, particularly lesser bandicoot rat (Bandicota
bengalensis) numbers. Since active rat burrows were recorded in an
average of 79% of the houses, but bandicoot rats were captured in
only 15 of 110 houses with bandicoot rat burrows (an average of
13.6%), it is obvious that rat traps are not taking this species in
numbers commensurate with its presence.

During a survey to determine postharvest stored food losses, S.
Ahmad, Vertebrate Pest Research Laboratory, BARI, talks to a
Bangladeshi farmer in the Tangail District who assisted in
measuring rat activity, trapping, and reporting amount of paddy
lost.

Table 25 summarizes tracking tile data for the first 7 months of the
study. About 65% of the positive tiles were on platforms or in
baskets, both before and after trapping.

When we examined animal captures, there was a distinct stratifica-
tion among different species. M. musculus was found at all levels,
but predominated on platforms. R. rattus preferred platforms and
baskets and was rarely taken on the fToor. B. bengalensis preferred

the floor and platforms, but can be found in baskets occasionally.
Suncus murinus occurred mainly on the floor and was infrequently
taken on platforms. These differences are summarized in Table 26.
Sixty-six percent of the captures occurred off the floor. There
was strong agreement between animal captures by location and
tracking tile activity by location.

The combined estimates for rodent species gave a mean of 10.2
rodents/structure, which was more than a threefold increase over
our previous estimates. These rats and mice can consume and hoard
70.7 kg of stored paddy/year/household.

Rice Husk Sweepings as a Measure of Rodent Consumption of Paddy in
Bhogra Village, Bangladesh

A study was done to determine the feasibility of using rice husk
sweepings, gathered daily from farmers' houses in Bhogra Village,
as a means of estimating rodent consumption of stored paddy.
Fifteen farmers agreed to save the daily rice husk sweepings from
their houses, but only 12 farmers provided enough samples over a

6-week period to collect meaningful data (Table 27). Most samples
were obtained from the floor, while much of the husks actually
accumulated on elevated storage platforms and in woven bamboo
storage baskets. Sweepings were placed in a plastic bag that was
picked up weekly. The proportional weight of the husk to the rice
grain was determined by examining 500 paddy grains; husks
constituted 26.3% of the total weight. Samples contained rodent
feces, thus, it could be determined which species--house mouse, roof
rat, or lesser bandicoot rat--infested each household. Mean paddy
storage per household at the start of the study on 24 September was
1,694 kg, which declined to 584 kg by 5 November, due to household
use and sale of rice.

a Totals include rice husks winnowed from 255
11 months, which indicated a loss of 8.7 kg

kg of paddy stored for
or 3.4%.

Mean weekly losses ranged from 162.2 g to 838.3 g. All houses were
infested with house mice, five with roof rats, and six with lesser
bandicoot rats. Examination of daily rice husk sweep samples is an
easy way to determine rodent infestation and species composition in
farm houses and more accurate than the use of tracking tiles or
traps, which, in these same houses, showed that only 64% were rodent
infested.

The mean loss of paddy/week/household was 348 g, which was minimal
because many husks were still lying on platforms and in woven
bamboo storage baskets that are cleaned infrequently, indicating a
possible annual loss of 18 kg/family. This estimate does not
include any paddy hoarded by lesser bandicoot rats in their burrows
in the foundation floors of farm houses.

Estimating Rodent Populations and Damage to Stored Wheat

At DWRC, a study involving closed colonies of house mice was
initiated to develop better methods for estimating rodent damage to
stored wheat. An assessment of the effects of mouse population
density on wheat consumption and contamination levels was needed to
evaluate previously proposed damage estimation techniques and the
utility of other measured variables (for example, water consumption
or photocell breaks) as indices of rodent activity and damage.

Two population density levels were compared. Fifty wild house mice
(25 male and 25 female adults) were released into a 34.2-m2 room
within a brick and concrete rodent-proofed building. At the same
time, 100 wild mice (50 male and 50 female adults) were released
into a second 34.2-m2 room in the same building. Both mouse
colonies were adapted to attached 1.7-m2 harborage areas and to
feeding on whole wheat in 1.2x1.5-m open wood storage bins. When
water and food consumption levels stabilized after 2 weeks, 114 kg
of winter wheat were placed in each open bin. During the next 30
days, mouse activity was measured twice weekly using water consump-
tion and photocell break counts as indices. Also, during this
period, two 8-day live trapping sequences were conducted to capture,
mark, and recapture individual mice. A census was made after a
30-day test period by capturing all the mice in each colony.
Pregnancy rates, body weights, and signs of fighting were assessed.
The wheat was reweighed and ten 25-g samples were taken from each
bin for evaluations of urine, droppings, and hair contamination).
The test procedure was then replicated with new groups of mice.

Preliminary results of these tests are summarized and compared with
estimated values in Table 28. Natural mortality from fighting and
low natality-pregnancy rates resulted in reduced colony populations
at the end of the 30-day period. The Lincoln-Peterson index was
used to estimate mean colony sizes from the capture-mark-recapture

data. Estimated values tended to be only about half of the actual
mean colony sizes. The weight of consumed wheat was probably biased
and distorted by urine and fecal contamination, but the results
indicated a trend toward lower consumption/mouse/day in the denser
(N = 100) colonies (3 and 4). Mean body weights of mice in the two
lower density (N = 50) colonies (1 and 2) also tended to be greater,
possibly because of less social stress. Based on the mean colony
sizes and the assumption recommended by J. H. Greaves that mice
consume approximately 15% of their body weights/day in grain, the
calculated estimates were generally below the measured food consump-
tion levels (12-47% lower). Overall, house mice in all colonies
consumed approximately 19.7% of their body weights/day in grain
under our test conditions.

Contamination data and population estimates based on water consump-
tion and photocell break data are being analyzed. Mean daily values
for these variables are shown in Table 28. The Lincoln-Peterson
index tended to underestimate population sizes. Colony sizes of 25
vs. 12 will be examined in the next phase of the research. When
completed, this experiment will provide an evaluation of the
reliability and 'accuracy of stored grain damage estimation via
population sampling, water consumption, and activity sensing
methods.

1 Fully funded under a Participating Agency Service Agreement
(PASA).
2 Personnel not funded under a PASA but who participated in work
associated with or pertinent to this project.
3 Foreign nationals associated with the project and funded by their
respective governments except as otherwise indicated.
4 Individuals who cooperated with the project in research, exten-
sion, or project development activities.

Bullard, R. W. and H. Stryker. 1984. "Improved grain storage and
pest control in El Salvador, evaluation and recommendations."
Report prepared for the U.S. Agency for International
Development, Department of State.

Fiedler, L. A. 1984. "Recommendations for reducing coconut losses
due to rodents in the Maldive Archipelago." Report prepared
for the Government of the Republic of the Maldives and the Food
and Agriculture Organization of the United Nations.

Fiedler, L. A. 1984. "The status of rodent control in five East
African countries." Report prepared for the Food and Agricul-
ture Organization of the United Nations.

Otis, D. L. 1984. "A method for estimating sorghum loss to birds
over large areas of eastern Africa." Report prepared for the
Food and Agriculture Organization of the United Nations.